Operating method and apparatus according to data duplicate retransmission in mobile communication system

ABSTRACT

An operating method and an apparatus according to data duplicate retransmission in a mobile communication system are provided. A method of a User Equipment (UE) according to data duplicate retransmission in a mobile communication system includes storing a Media Access Control Protocol Data Unit (MAC PDU) received from an Evolved Node B (ENB) in a soft buffer, decoding the MAC PDU, determining whether the decoding is a first successful decoding of data of the corresponding soft buffer, and determining whether to forward the decoded MAC PDU to an upper layer according to the determination result.

PRIORITY

This application claims the benefit under 35 U.S.C. §119(a) of a Koreanpatent application filed in the Korean Intellectual Property Office onMar. 24, 2009, and assigned Serial No. 10-2009-0025150 and a Koreanpatent application filed in the Korean Intellectual Property Office onApr. 10, 2009, and assigned Serial No. 10-2009-0031519, the entiredisclosures of both of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to an operating method and an apparatusaccording to data duplicate retransmission in a mobile communicationsystem. More particularly, the present invention relates to a method andan apparatus for a user equipment to determine duplicate retransmissionof downlink data and to prevent duplicate processing of thecorresponding data.

DESCRIPTION OF THE RELATED ART

Universal Mobile Telecommunication Service (UMTS) system is a 3^(rd)generation asynchronous mobile communication system using wideband CodeDivision Multiple Access (CDMA) based on Global System for MobileCommunications (GSM), which is a mobile communication system used acrossEurope, and General Packet Radio Services (GPRS).

The 3^(rd) Generation Partnership Project (3GPP) standardization of theUMTS system provides Long Term Evolution (LTE) as a next-generationmobile communication system of the UMTS system. The LTE technologyimplements rapid packet based communications at a maximum data rate ofapproximately 100 Mbps and plans to launch service around the year 2010.Accordingly, several solutions are provided for example, reducing anumber of nodes in a communication path by simplifying a networkstructure, and a method for approximating wireless protocols as close aspossible to the radio channel.

FIG. 1 illustrates a structure of a conventional LTE system.

Referring to FIG. 1, Evolved Radio Access Networks (E-RANs) 110 and 112are simplified to a two-node structure including Evolved Node Bs (ENBs)or Node Bs 120 through 128 and access gateways 130 and 132. A UserEquipment (UE) 101 accesses an Internet Protocol (IP) network 114 overthe E-RAN 110 and 112. The ENBs 120 through 128 are connected with theUE 101 via a radio channel, and perform a more complicated function thanthe existing node B.

The LTE system uses a Media Access Control (MAC) layer control signal,that is, a MAC Control Element (CE), for a control signal that is morereliable than a physical layer control signal and requires fasterprocessing than a Radio Link Control (RLC) layer control signal. Forexample, the LTE system uses a Timing Advance (TA) command MAC CE whichis the MAC layer control signal for the purpose of uplink transmissiontiming synchronization.

FIG. 2 illustrates conventional uplink transmission timingsynchronization using a TA command MAC CE in an LTE system.

Referring to FIG. 2, based on a Sounding Reference Signal (SRS) or aDeModulation Reference Signal (DMRS) received from a UE 200, an ENB 202measures an uplink timing offset in step 210. When determining whetherit is necessary to correct uplink timing offset or updating a TA timeraccording to the measurement of the uplink timing offset, the ENB 202transmits the TA command MAC CE to the UE 200 in step 212. The UE 200synchronizes the uplink timing with the ENB 202 using the received TAcommand in step 214 and transmits uplink channels PUCCH and PUSCH, anduplink signals based on the uplink timing corrected by the TA command instep 216.

Meanwhile, although the UE transmits ACK information with respect todownlink Hybrid Automatic Repeat reQuest (HARQ) data, the ENB canretransmit the downlink HARQ data because it determines the ACKinformation as NACK information or fails to receive the data. As aresult, the UE receives duplicated downlink HARQ data. Accordingly, aconventional LTE system does not provide a technique for detecting theduplicate reception of the data in the MAC layer. When receiving theduplicate MAC Protocol Data Unit (PDU), which is previously received andsuccessfully decoded, the UE conducts unnecessary operations to processthe duplicate MAC PDU received, which provides a system error. Forexample, when receiving the duplicate MAC PDU including the TA commandMAC CE, the UE does not recognize the duplicate reception. The UEre-synchronizes the uplink timing with the ENB using the duplicate TAcommand, which causes an error and compromises the uplink transmissiontiming synchronization.

Therefore, a need exists for an apparatus and method for detectingduplicate received data to prevent duplicate processing of a MAC PDU.

SUMMARY OF THE INVENTION

An aspect of the present invention is to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentinvention to provide an operating method and an apparatus according todata duplicate retransmission in a mobile communication system.

Another aspect of the present invention is to provide a method and anapparatus for determining whether a Media Access Control (MAC) ProtocolData Unit (PDU) is redundantly received and preventing duplicateprocessing of the MAC PDU which is previously processed in a Long TermEvolution (LTE) system supporting Hybrid Automatic Repeat reQuest(HARQ).

Yet another aspect of the present invention is to provide a method andan apparatus for preventing timing synchronization from beingcompromised by duplicate retransmission of data by adding a sequencenumber to a MAC layer control signal, such as a Timing Advance (TA)command MAC Control Element (CE) for uplink timing synchronization in anLTE system.

Still another aspect of the present invention is to provide a method andan apparatus for preventing data duplicate processing using HARQ relatedinformation of a MAC PDU including a MAC layer control signal, such as aTA command MAC CE for uplink timing synchronization in an LTE system.

A further aspect of the present invention is to provide a method and anapparatus for preventing duplicate processing of data by determiningwhether data of a HARQ soft buffer is successfully decoded in an LTEsystem.

In accordance with an aspect of the present invention, a method of aUser Equipment (UE) according to data duplicate retransmission in amobile communication system is provided. The method includes storing aMedia Access Control Protocol Data Unit (MAC PDU) received from anEvolved Node B (ENB) in a soft buffer, decoding the MAC PDU, determiningwhether the decoding is a first successful decoding of data of thecorresponding soft buffer, and determining whether to forward thedecoded MAC PDU to an upper layer according to the determination result.

In accordance with another aspect of the present invention, an apparatusof a UE according to data duplicate retransmission in a mobilecommunication system is provided. The apparatus includes a soft bufferfor storing a MAC PDU received from an ENB, a decoder for decoding theMAC PDU stored in the soft buffer, and a controller for determiningwhether the decoding is a first successful decoding of data of thecorresponding soft buffer, and determining whether to forward thedecoded MAC PDU to an upper layer according to the determination result.

In accordance with yet another aspect of the present invention, a methodof a UE according to data duplicate retransmission in a mobilecommunication system is provided. The method includes receiving a MACPDU, determining whether the MAC PDU comprises a control signal forcorrecting uplink timing synchronization, and if it is determined thatthe MAC PDU comprises the control signal, determining a duplicatereception of the control signal using a Sequence Number (SN) for thecontrol signal.

In accordance with still another aspect of the present invention, amethod of an ENB for data duplicate retransmission in a mobilecommunication system is provided. The method includes when an event forcorrecting uplink timing synchronization of a UE occurs, generating acontrol signal comprising an SN, and generating and transmitting a MACPDU comprising the control signal to the corresponding UE.

Other aspects, advantages, and salient features of the invention willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, feature, and advantages of certainexemplary embodiments of the present invention will be more apparentfrom the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 illustrates a structure of a conventional Long Term Evolution(LTE) system;

FIG. 2 illustrates a conventional uplink transmission timingsynchronization process using a Timing Advance (TA) command Media AccessControl (MAC) Control Element (CE) in an LTE system;

FIG. 3 illustrates signal flows for determining and processingduplication of a MAC Protocol Data Unit (PDU) using a sequence number inan LTE system according to an exemplary embodiment of the presentinvention;

FIG. 4 illustrates operations of a User Equipment (UE) for determiningand processing duplication of a MAC PDU using a sequence number in anLTE system according to an exemplary embodiment of the presentinvention;

FIG. 5 illustrates operations of an Evolved Node B (ENB) for generatingand transmitting a MAC PDU including a sequence number in an LTE systemaccording to an exemplary embodiment of the present invention;

FIG. 6 illustrates a TA command MAC CE in an LTE system according to anexemplary embodiment of the present invention;

FIG. 7 illustrates signal flows for determining and processingduplication of a MAC PDU using Hybrid Automatic Repeat reQuest (HARQ)information in an LTE system according to an exemplary embodiment of thepresent invention;

FIG. 8 illustrates operations of a UE for determining and processingduplication of a MAC PDU using HARQ information in an LTE systemaccording to an exemplary embodiment of the present invention;

FIGS. 9 through 12 illustrate processes of a UE for determining andprocessing duplication of a MAC PDU using HARQ information in an LTEsystem according to exemplary embodiments of the present invention;

FIGS. 13, 14 and 15 illustrate processes of a UE for determining andprocessing duplication of a MAC PDU using HARQ information in an LTEsystem according to exemplary embodiments of the present invention;

FIGS. 16 through 19 illustrate processes of a UE for determining andprocessing duplication of a MAC PDU using HARQ information in an LTEsystem according to exemplary embodiments of the present invention;

FIGS. 20, 21 and 22 illustrate processes of a UE for determining andprocessing duplication of a MAC PDU using HARQ information in an LTEsystem according to exemplary embodiments of the present invention;

FIGS. 23, 24 and 25 illustrate processes of a UE for determining andprocessing duplication of a MAC PDU using HARQ information in an LTEsystem according to exemplary embodiments of the present invention;

FIG. 26 is a block diagram of a UE in an LTE system according to anexemplary embodiment of the present invention; and

FIG. 27 is a block diagram of an ENB in an LTE system according to anexemplary embodiment of the present invention.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components and structures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of exemplaryembodiments of the invention as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of theinvention. Also, descriptions of well-known functions and constructionsare omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of theinvention. Accordingly, it should be apparent to those skilled in theart that the following description of exemplary embodiments of thepresent invention are provided for illustration purpose only and not forthe purpose of limiting the invention as defined by the appended claimsand their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

Exemplary embodiments of the present invention provide a method and anapparatus for preventing duplicate processing of a Media Access ControlProtocol Data Unit (MAC PDU) that is previously processed by determiningat a User Equipment (UE) whether duplication of the MAC PDU is receivedin a Long Term Evolution (LTE) system supporting Hybrid Automatic RepeatreQuest (HARQ). Herein, when the UE transmits ACKnowledgement (ACK)information for the MAC PDU and an Evolved Node B (ENB) retransmits theMAC PDU because it determined the ACK information as NegativeACKnowledgement (NACK) information or it failed to receive the MAC PDU,the UE redundantly receives the MAC PDU, which is referred to as MAC PDUduplication.

In an exemplary implementation, by adding a sequence number to a TimingAdvance (TA) command MAC Control Element (CE), which is a control signalof the MAC layer for uplink timing synchronization, duplicate processingof the TA command MAC CE, that is the duplication of the MAC PDUincluding the TA command MAC CE, is prevented.

FIG. 3 illustrates signal flows for determining and processingduplication of a MAC PDU using a sequence number in an LTE systemaccording to an exemplary embodiment of the present invention.

Referring to FIG. 3, a UE 300 transmits a Sounding Reference Signal(SRS) or a DeModulation Reference Signal (DMRS) to an ENB 302 using aresource allocated by the ENB 302 in step 310. The ENB 302 verifies anuplink timing offset using the SRS or the DMRS of the UE 300 anddetermines whether it is necessary to correct the uplink timing offset.When the uplink timing offset needs to be corrected, the ENB 302generates and transmits the TA command MAC CE including a SequenceNumber (SN) to the UE 300 in step 312. Herein, the TA command MAC CEincludes 2-bit SN or reservation information SN0 or R 601 and SN1 or R603, and 6-bit TA command information 605 as illustrated in FIG. 6. TheSN0 or SN1 indicates the SN, and the R denotes the reserved information.When the system uses the 2-bit SN, both of SN0 or R 601 and SN1 or R 603may be used as the SN. When the system uses 1-bit SN, one of SN0 or R601 and SN1 or R 603 may be used as the bit for the SN and the other maybe used for the bit for the reserved information.

The UE 300 receiving the TA command MAC CE determines the SN of the TAcommand MAC CE and compares the determined SN with a SN of a previouslyreceived TA command MAC CE. When the two SNs are different, the UE 300determines that the TA command MAC CE is not duplicated and corrects theuplink timing by applying the received TA command in step 314. In step316, the UE 300 transmits ACK information to the ENB 302 to inform of asuccessful reception of the TA command MAC CE.

When it is determined that the ACK information is NACK information, theENB 302 retransmits the MAC PDU including the TA command MAC CE with theSN to the UE 300 in step 318. Upon receiving the retransmitted MAC PDU,the UE 300 determines the SN in the TA command MAC CE of the receivedMAC PDU and compares the determined SN with the SN of the previous TAcommand MAC PDU. When the two SNs are the same, the UE 300 determinesthat the TA command MAC CE is duplicated and discards the TA command MACCE without processing it in step 320.

FIG. 4 illustrates operations of a UE for determining and processing aMAC PDU duplication using an SN in an LTE system according to anexemplary embodiment of the present invention.

Referring to FIG. 4, in step 401, the UE transmits an SRS or DMRS to anENB. After transmitting the SRS or the DMRS to the ENB in step 401, theUE receives a MAC PDU from the ENB in step 403.

In step 405, the UE determines whether the MAC PDU includes a TA commandMAC CE. Herein, the UE may determine whether the MAC PDU includes the TAcommand MAC CE, based on a logical channel IDentifier (ID) of a MACheader. When it is determined that the MAC PDU does not include the TAcommand MAC CE, the UE processes contents of the MAC PDU in step 407 andreturns to step 403 to repeat the subsequent step.

When it is determined that the MAC PDU includes the TA command MAC CE,the UE confirms the SN of the TA command MAC CE, compares the SN withthe SN of the previously received TA command MAC CE, and thus determineswhether the two SNs are the same in step 409. Herein, in a case of aninitially received TA command MAC CE, the SN is not previously received.The UE may determine the different SNs. By pre-defining an SN unused bythe ENB as an initial SN, the UE may provide two different SNs in theinitial reception of the TA command MAC CE.

When the two SNs are the same, the UE determines the duplication of theMAC PDU including the TA command MAC CE and discards the received TAcommand MAC CE in step 415. The UE proceeds to step 407.

By contrast, when the two SNs are different, the UE synchronizes theuplink timing by applying the TA command of the TA command MAC CE instep 411, stores the SN of the TA command MAC CE in step 413, andproceeds to step 407.

FIG. 5 illustrates operations of an ENB for generating and transmittinga MAC PDU including an SN in an LTE system according to an exemplaryembodiment of the present invention.

Referring to FIG. 5, in step 501, the ENB receives an SRS or a DMRS froma UE. After receiving the SRS or the DMRS from the UE in step 501, theENB measures an uplink timing offset using the received SRS or DMRS instep 503. The ENB determines whether it is necessary to correct theuplink timing offset in step 505. When the correction is unnecessary,the ENB generates and transmits the MAC PDU in step 507 and ends theprocess.

When the uplink timing offset needs to be corrected, the ENB increasesthe SN in step 509 and determines whether the increased SN is greaterthan a preset maximum in step 511. When the increased SN is greater thanthe preset maximum, the ENB initializes the SN in step 515 and proceedsto step 513. The SN is initialized to a preset minimum.

When it is determined that the increased SN is not greater than thepreset maximum, the ENB generates a TA command MAC CE including theincreased SN in step 513. In step 507, the ENB generates and transmitsto the UE the MAC PDU including the generated TA command MAC CE, andends the process.

By preventing the duplicate processing of the TA command MAC CE usingthe SN as described in FIGS. 3 through 6, compromise of the uplinktiming synchronization may be avoided and the uplink data and signal maybe reliably transmitted.

In a case of the MAC PDU duplication including the TA command MAC CE,the duplicate processing of the TA command MAC CE may be prevented byuse of HARQ related information of the MAC PDU as described in moredetail below. The ENB operates similarly to a conventional LTE system.Herein, the HARQ related information includes at least one ofinformation indicating whether data of a HARQ soft buffer is a firstcase of successful decoding, information indicating whether an initialdecoding is successful after determining whether HARQ data is initiallytransmitted, soft buffer update information, New Data Indicator (NDI)information, and information indicating whether previously received datais successfully decoded and size information of the previously receivedand the currently received data.

FIG. 7 illustrates signal flows for determining and processingduplication of a MAC PDU using HARQ information in an LTE systemaccording to an exemplary embodiment of the present invention.

Referring to FIG. 7, the ENB 702 transmits downlink HARQ data to the UE700 in step 710. Accordingly, the ENB 702 may include a TA command MACCE to correct an uplink timing synchronization into the downlink HARQdata. In step 712, the UE 700 receiving the downlink HARQ data transmitsACK information to the ENB 702 to inform of successful reception of thedownlink HARQ data.

However, if it is determined that the ACK information is NACKinformation, the ENB 702 retransmits the downlink HARQ data in step 714.The ENB 702 may indicate that the corresponding MAC PDU is retransmitteddata by including NDI information of the retransmitted downlink HARQdata to a Physical Downlink Control CHannel (PDCCH). That is, the NDIinformation specifies whether the current packet data is initiallytransmitted packet data or retransmitted packet data. When the NDIinformation is ‘0’, the packet data is initially transmitted. When theNDI information is ‘1’, it may indicate retransmitted packet data.Alternatively, the initially transmitted data or the retransmitted datamay be represented using an increment of the NDI value or toggling. Whenthe NDI is different or increased from a previous value, this indicatesinitial transmission of the packet data. The same NDI information as theprevious value may indicate the retransmission of the packet data. Inthis case, when the size of the transmitted data is different regardlessof the same NDI value, the ENB may determine the initially transmittedpacket data.

In step 716, the UE 700 determines whether the downlink HARQ data isduplicated, based on the HARQ related information of the retransmitteddownlink HARQ data. Herein, the determining of whether the downlink HARQdata is duplicated may utilize a method for determining whether data ofa HARQ soft buffer is a first case of successful decoding, a method fordetermining whether an initial decoding is successful after determiningwhether the HARQ data is initially transmitted, a method for determiningwhether data of the HARQ soft buffer is updated by replacing orcombining the data with the currently received data, or a method fordetermining whether received data is retransmitted and the previous datain a soft buffer is successfully decoded, and for comparing the size ofthe currently received data with the size of the previous data. Herein,if it is determined that the downlink HARQ data is duplicated, the UE700 discards the TA command MAC CE of the downlink HARQ data withoutprocessing. If it is determined that the downlink HARQ data is notduplicated, the UE 700 synchronizes uplink timing by processing the TAcommand MAC CE of the downlink HARQ data.

The UE 700 transmits ACK information to the ENB 702 in step 718.

FIG. 8 illustrates operations of a UE for determining and processingduplication of a MAC PDU using HARQ information in an LTE systemaccording to an exemplary embodiment of the present invention.

Referring to FIG. 8, in step 801, the UE transmits an SRS or a DMRS.After transmitting the SRS or the DMRS in step 801, the UE receives theHARQ data, that is, the MAC PDU from an ENB in step 803.

Based on the HARQ related information for the received HARQ data, the UEdetermines whether the HARQ data is duplicated and stores thedetermination result in step 805. Herein, if it is determined that theHARQ data is duplicated, the UE may utilize the method for determiningwhether data of the HARQ soft buffer is a first case of successfuldecoding, the method for determining whether initial decoding issuccessful after determining whether the HARQ data is initiallytransmitted, the method for determining whether the data of the HARQsoft buffer is updated by replacing or combining the data with currentlyreceived data, or the method for determining whether the received datais retransmitted and the previous data of the soft buffer issuccessfully decoded, and for comparing the size of the currentlyreceived data with the size of the previous data. Herein, the method fordetermining the duplication of the HARQ data is described in more detailwith reference to FIGS. 9 through 25.

In step 807, the UE determines whether the MAC PDU includes a TA commandMAC CE. Herein, whether the TA command MAC CE is included may bedetermined based on a logical channel ID of the MAC header. When it isdetermined that the MAC PDU does not include the TA command MAC CE, theUE processes the data in the MAC PDU in step 809 and returns to step 803to repeat the subsequent step.

When it is determined that the MAC PDU includes the TA command MAC CE,the UE verifies the stored duplication in step 811.

When confirming the duplication, the UE discards the TA command MAC CEof the MAC PDU in step 815. The UE proceeds to step 809. By contrast,when confirming that there is no duplication, the UE synchronizes anuplink timing by applying the TA command of the TA command MAC CE of theMAC PDU in step 813 and proceeds to step 809.

Herein, the UE determines whether to apply or discard the TA commandaccording to the duplication of the HARQ and also may vary the operationin step 809, that is, the processing of other data in the MAC PDU, whichwill be described in more detail with reference to FIGS. 9 and 25.

FIGS. 9 through 25 provide a method of the UE for determining whethercorresponding HARQ data is duplicated using HARQ related information,and a method for processing corresponding data according to theduplication result.

A method for the UE to determine and process the duplication of thecorresponding HARQ data using the decoding result of the HARQ data andthe size of the data is described with reference to FIGS. 9 through 12.

FIG. 9 illustrates operations of a UE for determining and processingduplication of a MAC PDU using HARQ information in an LTE systemaccording to an exemplary embodiment of the present invention.

Referring to FIG. 9, the UE receives downlink HARQ data from an ENB instep 901. In step 903, the UE confirms the HARQ information. Herein, theHARQ information includes NDI information indicating whether currentlytransmitted data is initially transmitted data or retransmitted data.

In step 905, the UE determines whether the received data isretransmitted data, based on the HARQ information.

When it is determined that the received data is initially transmitteddata rather than retransmitted data, the UE replaces and stores thereceived data in a soft buffer of a corresponding HARQ in step 907 andproceeds to step 909. By contrast, when it is determined that thereceived data is retransmitted data, the UE determines whether theprevious data of the corresponding HARQ is successfully decoded in step915.

When it is determined that the previous data of the corresponding HARQis not successfully decoded, the UE combines the received data with theprevious data of the soft buffer of the corresponding HARQ and storesthe combined data in order to increase a decoding success rate of thedata in step 917, and proceeds to step 909. By contrast, when it isdetermined that the previous data of the corresponding HARQ issuccessfully decoded, the UE determines whether the previous data of thecorresponding HARQ is the same size as the received data in step 923.

When it is determined that the sizes of the previous data of thecorresponding HARQ and the received data are not the same, the UEdetermines that the received data, which is the retransmitted data,differs from the previous data, replaces and stores the received data ina soft buffer of a corresponding HARQ in step 925, and proceeds to step909.

When it is determined that the sizes of the previous data of thecorresponding HARQ and the received data are the same, the UE determinesthe received data is duplicated, discards the received data in step 927,proceeds to step 921 without decoding, and generates and transmits ACKinformation for the corresponding HARQ data to the ENB in step 921. Assuch, the decoding of the duplicate data may be omitted, and anadditional operations and a malfunction caused by the duplication may beavoided. Herein, the discarding of the received data in step 927 may beomitted in the operation.

The UE decodes the data in the soft buffer in step 909 and determineswhether the decoding is successful in step 911. When it is determinedthat the decoding is successful, the UE forwards the decoded MAC PDU toa corresponding MAC disassembly and demultiplexing entity or to an upperlayer in step 919, and generates and transmits ACK information for thecorresponding HARQ data to the ENB in step 921.

When it is determined that the decoding fails, the UE generates andtransmits NACK information for the corresponding HARQ data to the ENB instep 913.

The UE ends the process.

In FIG. 9, disadvantageously, when the data retransmitted and receivedis not successfully decoded and is different from previous data in size,that is, when the retransmitted data differs from the previous data, theretransmitted data may be combined with the data in the previous softbuffer and then decoded together. To overcome this drawback, variousprocesses of the UE are described in more detail with reference to FIGS.10, 11 and 12.

FIG. 10 illustrates a process of a UE for determining and processingduplication of a MAC PDU using HARQ information in an LTE systemaccording to an exemplary embodiment of the present invention.

Referring to FIG. 10, the UE receives downlink HARQ data from the ENB instep 1001. In step 1003, the UE confirms the HARQ information, that is,NDI information.

In step 1005, the UE determines whether the received data isretransmitted data, based on the HARQ information. When it is determinedthat the received data is initially transmitted data rather thanretransmitted data, the UE replaces and stores the received data in asoft buffer of a corresponding HARQ in step 1007 and proceeds to step1009.

By contrast, when it is determined that the received data isretransmitted data, the UE determines whether the previous data of thecorresponding HARQ is the same size as the received data in step 1015.When it is determined that the sizes of the previous data of thecorresponding HARQ and the received data are not the same, the UEdetermines that the received data, which is the retransmitted data,differs from the previous data, replaces and stores the received data inthe soft buffer of the corresponding HARQ in step 1017, and proceeds tostep 1009.

When it is determined that the sizes of the previous data of thecorresponding HARQ and the received data are the same, the UE determineswhether the previous data of the corresponding HARQ is successfullydecoded in step 1023. When it is determined that the previous data ofthe corresponding HARQ is not successfully decoded, the UE combines thereceived data with previous data in the soft buffer of the correspondingHARQ and stores the combined data in order to increase a decodingsuccess rate of the data in step 1025, and proceeds to step 1009.

By contrast, when it is determined that the previous data of thecorresponding HARQ is successfully decoded, the UE determines if thereceived data is duplicated, discards the received data in step 1027,and generates and transmits ACK information for the corresponding HARQdata to the ENB without decoding in step 1021.

The UE decodes the data in the soft buffer in step 1009 and determineswhether the decoding is successful in step 1011. When it is determinedthat the decoding is successful, the UE forwards the decoded MAC PDU tothe corresponding MAC disassembly and demultiplexing entity or to anupper layer in step 1019, and generates and transmits ACK informationfor the corresponding HARQ data to the ENB in step 1021.

When it is determined that the decoding fails, the UE generates andtransmits NACK information for the corresponding HARQ data to the ENB instep 1013.

The UE ends the process.

FIG. 11 illustrates a process of a UE for determining and processingduplication of MAC PDU using HARQ information in an LTE system accordingto an exemplary embodiment of the present invention.

Referring to FIG. 11, the UE receives downlink HARQ data from an ENB instep 1101. In step 1103, the UE confirms the HARQ information, that is,NDI information.

In step 1105, the UE determines whether the received data isretransmitted data, based on the HARQ information.

When it is determined that the received data is initially transmitteddata rather than retransmitted data, the UE replaces and stores thereceived data in a soft buffer of a corresponding HARQ in step 1107 andproceeds to step 1109. By contrast, when it is determined that thereceived data is retransmitted data, the UE determines whether previousdata of the corresponding HARQ is successfully decoded in step 1115.

When it is determined that the previous data of the corresponding HARQis not successfully decoded, the UE combines the received data with theprevious data of the soft buffer of the corresponding HARQ and storesthe combined data in order to increase a decoding success rate of thedata in step 1117, and proceeds to step 1123. By contrast, when it isdetermined that the previous data of the corresponding HARQ issuccessfully decoded, the UE determines whether the previous data of thecorresponding HARQ is the same size as the received data in step 1123.

When it is determined that the sizes of the previous data of thecorresponding HARQ and the received data are not the same, the UEdetermines that the received data, which is the retransmitted data,differs from the previous data, replaces and stores the received data inthe soft buffer of the corresponding HARQ in step 1125, and proceeds tostep 1109.

When it is determined that the sizes of the previous data of thecorresponding HARQ and the received data are the same, the UE determineswhether the received data is duplicated in step 1127. Herein, the UE maydetermine the duplication using the method for determining whether dataof the HARQ soft buffer is a first case of successful decoding, themethod for determining whether the initial decoding is successful afterdetermining whether the HARQ data is initially transmitted, the methodfor determining whether the data of the HARQ soft buffer is updated byreplacing or combining the data with the currently received data, or themethod for determining whether the received data is retransmitted andthe previous data of the soft buffer is successfully decoded, and forcomparing the size of the currently received data with the size of theprevious data. When it is determined that there is not a duplication,the UE proceeds to step 1109. When it is determined that there is aduplication, the UE discards the received data in step 1129, andgenerates and transmits ACK information for the corresponding HARQ datato the ENB without decoding in step 1121.

The UE decodes the data in the soft buffer in step 1109 and determineswhether the decoding is successful in step 1111. When it is determinedthat the decoding is successful, the UE forwards the decoded MAC PDU tothe corresponding MAC disassembly and demultiplexing entity or to anupper layer in step 1119, and generates and transmits ACK informationfor the corresponding HARQ data to the ENB in step 1121.

When it is determined that the decoding fails, the UE generates andtransmits NACK information for the corresponding HARQ data to the ENB instep 1113.

The UE ends the process.

FIG. 12 illustrates a process of a UE for determining and processingduplication of a MAC PDU using HARQ information in an LTE systemaccording to an exemplary embodiment of the present invention.

Herein, since the UE performs substantially similar operations as inFIG. 11, its operations in steps 1201-1223 and 1229 will not beillustrated in further detail. Yet, when previous data is not the sameas the currently received data, the received data is replaced and storedin the soft buffer and the data of the soft buffer is decoded in FIG.11. However, in FIG. 12, after received data is replaced and stored in asoft buffer in step 1225, a UE examines duplication of the received datain step 1227, rather than decode the data of the soft buffer in step1209.

In an exemplary embodiment of the present invention, in FIGS. 9 through12, additional decoding is prevented by determining whether receiveddata is duplicated. Thus, unnecessary operations may be omitted.However, unlike a HARQ operation for retransmitted data in aconventional system, it is not normal to transmit ACK informationwithout decoding corresponding soft buffer data of the retransmitteddata. Hence, processes for preventing duplicate processing of a MAC PDUwhile maintaining the HARQ operation of the conventional system aredescribed below in more detail with reference to FIGS. 13, 14 and 15.When the duplication of the received data is determined, in FIGS. 13, 14and 15, the decoded MAC PDU is blocked from forwarding data to acorresponding MAC disassembly and demultiplexing entity or an upperlayer.

FIG. 13 illustrates a process of a UE for determining and processingduplication of a MAC PDU using HARQ information in an LTE systemaccording to an exemplary embodiment of the present invention.

Referring to FIG. 13, the UE receives downlink HARQ data from an ENB instep 1301. In step 1303, the UE confirms the HARQ information, that is,NDI information. In step 1305, the UE determines whether received datais retransmitted data, based on the HARQ information.

When it is determined that the received data is initially transmitteddata rather than retransmitted data, the UE replaces and stores thereceived data in a soft buffer of a corresponding HARQ in step 1307 andproceeds to step 1309. By contrast, when it is determined that thereceived data is retransmitted data, the UE determines whether previousdata of the corresponding HARQ is successfully decoded in step 1315.

When it is determined that the previous data of the corresponding HARQis not successfully decoded, the UE combines the received data with theprevious data of the soft buffer of the corresponding HARQ and storesthe combined data in order to increase a decoding success rate of thedata in step 1317, and proceeds to step 1309. By contrast, when it isdetermined that the previous data of the corresponding HARQ issuccessfully decoded, the UE determines whether the previous data of thecorresponding HARQ is the same size as the received data in size in step1321.

When it is determined that the sizes of the previous data of thecorresponding HARQ and the received data are not the same, the UEdetermines that the received data, which is the retransmitted data,differs from the previous data, replaces and stores the received data inthe soft buffer of the corresponding HARQ in step 1323, and proceeds tostep 1309.

When it is determined that the sizes of the previous data of thecorresponding HARQ and the received data are the same, the UE determineswhether the received data is duplicated, discards the received datawithout storing the received data in the soft buffer in step 1329, andproceeds to step 1309.

The UE decodes the data in the soft buffer in step 1309 and determineswhether the decoding is successful in step 1311. When it is determinedthat the decoding fails, the UE generates and transmits NACK informationfor the corresponding HARQ data to the ENB in step 1313.

When it is determined that the decoding is successful, the UE determineswhether the decoded data is duplicated data in step 1319. Herein, the UEmay determine the duplication using the method for determining whetherdata of the HARQ soft buffer is a first case of successful decoding, themethod for determining whether the initial decoding is successful afterdetermining whether the HARQ data is initially transmitted, the methodfor determining whether the data of the HARQ soft buffer is updated byreplacing or combining the data with the currently received data, or themethod for determining whether the received data is retransmitted andthe previous data of the soft buffer is successfully decoded, and forcomparing the size of the currently received data with the size of theprevious data.

When it is determined that the decoded data is not duplicated, the UEforwards the decoded MAC PDU to a corresponding MAC disassembly anddemultiplexing entity or to an upper layer in step 1325, and proceeds tostep 1327. When it is determined that the decoded data is duplicated,the UE generates and transmits ACK information for the correspondingHARQ data to the ENB in step 1327.

The UE ends the process.

In FIG. 13, when the data retransmitted and received is not successfullydecoded and has a different data size, that is, when the retransmitteddata differs from the previous data, it is disadvantageous that theretransmitted data may be combined and decoded with the data in aprevious soft buffer. To overcome this shortcoming, various processes ofthe UE are described in more detail with reference to FIGS. 14 and 15.

FIG. 14 illustrates a process of a UE for determining and processingduplication of a MAC PDU using HARQ information in an LTE systemaccording to an exemplary embodiment of the present invention.

Referring to FIG. 14, the UE receives downlink HARQ data from an ENB instep 1401. In step 1403, the UE confirms HARQ information, that is, NDIinformation. In step 1405, the UE determines whether the received datais retransmitted data, based on the HARQ information.

When it is determined that the received data is initially transmitteddata rather than retransmitted data, the UE replaces and stores thereceived data in a soft buffer of a corresponding HARQ in step 1407 andproceeds to step 1409. By contrast, when it is determined that thereceived data is retransmitted data, the UE determines whether previousdata of the corresponding HARQ is the same size as the received data instep 1415. When it is determined that the sizes of the previous data ofthe corresponding HARQ and the received data are not the same, the UEdetermines that the received data, which is the retransmitted data,differs from the previous data, replaces and stores the received data inthe soft buffer of the corresponding HARQ in step 1417, and proceeds tostep 1409.

When it is determined that the sizes of the previous data of thecorresponding HARQ and the received data are the same, the UE determineswhether the previous data of the corresponding HARQ is successfullydecoded in step 1421. When it is determined that the previous data ofthe corresponding HARQ is not successfully decoded, the UE combines thereceived data with the previous data in the soft buffer of thecorresponding HARQ and stores the combined data in order to increase adecoding success rate of the data in step 1423, and proceeds to step1409. By contrast, when it is determined that the previous data of thecorresponding HARQ is successfully decoded, the UE determines that thereceived data is duplicated, discards the received data without storingthe received data in the soft buffer in step 1429, and proceeds to step1409.

The UE decodes the data in the soft buffer in step 1409 and determineswhether the decoding is successful in step 1411. When it is determinedthat the decoding fails, the UE generates and transmits NACK informationfor the corresponding HARQ data to the ENB in step 1413.

When it is determined that the decoding is successful, the UE determineswhether the decoded data is duplicate data in step 1419. Herein, the UEmay determine the duplication using the method for determining whetherthe data of the HARQ soft buffer is a first case of successful decoding,the method for determining whether initial decoding is successful afterdetermining whether the HARQ data is initially transmitted, the methodfor determining whether the data of the HARQ soft buffer is updated byreplacing or combining the data with the currently received data, or themethod for determining whether the received data is retransmitted andthe previous data of the soft buffer is successfully decoded, and forcomparing the size of the currently received data with the size of theprevious data.

When it is determined that the decoded data is not duplicated, the UEforwards the decoded MAC PDU to a corresponding MAC disassembly anddemultiplexing entity or to an upper layer in step 1425, and proceeds tostep 1427. When it is determined that the decoded data is duplicated,the UE generates and transmits ACK information for the correspondingHARQ data to the ENB in step 1427.

The UE ends the process.

FIG. 15 illustrates a process of a UE for determining and processingduplication of a MAC PDU using HARQ information in an LTE systemaccording to an exemplary embodiment of the present invention.

Herein, since the UE performs substantially similar operations as inFIG. 13, its operations in steps 1501-1515, 1519 and 1523-1527 will notbe illustrated in further detail. Yet, in FIG. 15, after combining andstoring received data with previous data of a soft buffer in step 1517,the UE determines whether previously received data is the same size asthe received data in step 1521, rather than decode the data in the softbuffer in step 1509.

FIGS. 16 through 19 illustrate a technique for preventing a malfunctionor an additional operation for a duplicated MAC PDU by processingretransmitted data as in a conventional system and informing a MACdisassembly and demultiplexing entity or an upper layer of theduplication of the received data.

FIG. 16 illustrates a process of a UE for determining and processingduplication of a MAC PDU using HARQ information in an LTE systemaccording to an exemplary embodiment of the present invention.

Referring to FIG. 16, the UE receives the downlink HARQ data from an ENBin step 1601. In step 1603, the UE confirms the HARQ information, thatis, NDI information, and applies and initializes a duplication indicator(hereafter, referred to as dup_ind) indicative of the duplication of theMAC PDU of a corresponding HARQ in step 1603.

In step 1605, the UE determines whether the received data isretransmitted data, based on the HARQ information. When it is determinedthat the received data is initially transmitted data rather than theretransmitted data, the UE replaces and stores the received data in asoft buffer of a corresponding HARQ in step 1607 and proceeds to step1609. By contrast, when it is determined that the received data isretransmitted data, the UE determines whether previous data of thecorresponding HARQ is successfully decoded in step 1615.

When it is determined that the previous data of the corresponding HARQis not successfully decoded, the UE combines the received data with theprevious data in the soft buffer of the corresponding HARQ and storesthe combined data in order to increase a decoding success rate of thedata in step 1617, and proceeds to step 1609. By contrast, when it isdetermined that the previous data of the corresponding HARQ issuccessfully decoded, the UE determines whether the previous data of thecorresponding HARQ is the same size as the received data in step 1623.

When it is determined that the sizes of the previous data of thecorresponding HARQ and the received data are not the same, the UEdetermines that the received data, which is the retransmitted data,differs from the previous data, replaces and stores the received data inthe soft buffer of the corresponding HARQ in step 1625, and proceeds tostep 1609.

When it is determined that the sizes of the previous data of thecorresponding HARQ and the received data are the same, the UE determinesthat the received data is duplicated, discards the received data in step1627, sets the initialized dup_ind in step 1629, and proceeds to step1609.

The UE decodes the data in the soft buffer in step 1609 and determineswhether the decoding is successful in step 1611. When it is determinedthat the decoding is successful, the UE forwards the decoded MAC PDU andthe set dup_ind to a corresponding MAC disassembly and demultiplexingentity or to an upper layer in step 1619, and generates and transmitsACK information for the corresponding HARQ data to the ENB in step 1621.Herein, the MAC disassembly and demultiplexing entity or the upper layerreceiving the MAC PDU may verify the dup_ind value and discard the MACPDU when the dup_ind value indicates the duplication.

When it is determined that the decoding fails, the UE generates andtransmits NACK information for the corresponding HARQ data to the ENB instep 1613.

The UE ends the process.

FIG. 17 illustrates a process of a UE for determining and processingduplication of a MAC PDU using HARQ information in an LTE systemaccording to an exemplary embodiment of the present invention.

Herein, since the UE performs substantially similar operations as inFIG. 16, its operations in steps 1701-1713, 1717-1721 and 1725-1729 willnot be illustrated in further detail. Yet, in FIG. 16, after the UEdetermines whether the decoding of the previous data is successful instep 1615, in step 1623, the size of the previous data is compared withthe size of the current data when the decoding is successful. In FIG.17, the UE determines whether the decoding of the previous data issuccessful in step 1723 after comparing the sizes of the previous dataand the current data in step 1715.

FIG. 18 illustrates a process of a UE for determining and processingduplication of a MAC PDU using a HARQ information in an LTE systemaccording to an exemplary embodiment of the present invention.

Referring to FIG. 18, the UE receives downlink HARQ data from an ENB instep 1801. In step 1803, the UE confirms the HARQ information, that is,NDI information, and applies and initializes the dup_ind indicative ofthe duplication of the MAC PDU of the corresponding HARQ.

In step 1805, the UE determines whether the received data isretransmitted data, based on the HARQ information. When it is determinedthat the received data is initially transmitted data rather thanretransmitted data, the UE replaces and stores the received data in asoft buffer of a corresponding HARQ in step 1807 and proceeds to step1809. By contrast, when it is determined that the received data isretransmitted data, the UE determines whether the previous data of thecorresponding HARQ is successfully decoded in step 1815.

When it is determined that the previous data of the corresponding HARQis not successfully decoded, the UE combines the received data withprevious data of the soft buffer of the corresponding HARQ and storesthe combined data in order to increase a decoding success rate of thedata in step 1817, and proceeds to step 1823. By contrast, when it isdetermined that the previous data of the corresponding HARQ issuccessfully decoded, the UE determines whether the previous data of thecorresponding HARQ is the same size as the received data in step 1823.

When it is determined that the sizes of the previous data of thecorresponding HARQ and the received data are not the same, the UEdetermines that the received data, which is the retransmitted data,differs from the previous data, replaces and stores the received data inthe soft buffer of the corresponding HARQ in step 1825, and proceeds tostep 1809.

When it is determined that the sizes of the previous data of thecorresponding HARQ and the received data are the same, the UE determineswhether the received data is duplicated in step 1827. Herein, the UE maydetermine the duplication using the method for determining whether thedata of the HARQ soft buffer is a first case of successful decoding, themethod for determining whether the initial decoding is successful afterdetermining whether the HARQ data is initially transmitted, the methodfor determining whether the data of the HARQ soft buffer is updated byreplacing or combining the data with the currently received data, or themethod for determining whether the received data is retransmitted andthe data of the soft buffer is successfully decoded before, and forcomparing the size of the currently received data with that of theprevious data.

When it is determined that the receive data is not duplicated, the UEproceeds to step 1809. When it is determined that the received data isduplicated, the UE discards the received data in step 1829, sets theinitialized dup_ind in step 1831, and proceeds to step 1809.

The UE decodes the data in the soft buffer in step 1809 and determineswhether the decoding is successful in step 1811. When it is determinedthat the decoding is successful, the UE forwards the decoded MAC PDU andthe set dup_ind to a corresponding MAC disassembly and demultiplexingentity or to an upper layer in step 1819, and generates and transmitsACK information for the corresponding HARQ data to the ENB in step 1821.Herein, the MAC disassembly and demultiplexing entity or the upper layerreceiving the MAC PDU may verify the dup_ind value and discard the MACPDU when the dup_ind value indicates the duplication.

When it is determined that the decoding fails, the UE generates andtransmits NACK information for the corresponding HARQ data to the ENB instep 1813.

The UE ends the process.

FIG. 19 illustrates a process of a UE for determining and processingduplication of a MAC PDU using HARQ information in an LTE systemaccording to an exemplary embodiment of the present invention.

Herein, since the UE performs substantially similar operations as inFIG. 18, its operations in steps 1901-1923, 1929 and 1931 will not beillustrated in further detail. Yet, when the previous data is not thesame size as the currently received data in step 1823, the received datais replaced and stored in the soft buffer in step 1825 and the data ofthe soft buffer is decoded in step 1809 in FIG. 18. In comparison, thereceived data is replaced and stored in a soft buffer in step 1925, anda UE determines whether the received data is duplicated in step 1927 inFIG. 19, rather than decode the data of the soft buffer in step 1909.

FIGS. 20, 21 and 22 illustrate a technique for preventing a malfunctionor an additional operation for a duplicated MAC PDU by processingretransmitted data as in a conventional system and informing a MACdisassembly and demultiplexing entity or an upper layer of a soft bufferupdate.

FIG. 20 illustrates a process of a UE for determining and processingduplication of a MAC PDU using HARQ information in an LTE systemaccording to an exemplary embodiment of the present invention.

Referring to FIG. 20, the UE receives downlink HARQ data from an ENB instep 2001. In step 2003, the UE confirms the HARQ information, that is,NDI information, and applies and initializes a soft buffer updateindicator (hereafter, referred to as buffer_update_ind) indicative ofthe update of the soft buffer of a corresponding HARQ. An initial valueof the buffer_update_ind indicates that the soft buffer is not updated.

In step 2005, the UE determines whether the received data isretransmitted data, based on the HARQ information. When it is determinedthat the received data is initially transmitted data rather thanretransmitted data, the UE replaces and stores the received data in thesoft buffer of a corresponding HARQ and sets the buffer_update_ind instep 2007, and proceeds to step 2009. By contrast, when it is determinedthat the received data is retransmitted data, the UE determines whetherthe previous data of the corresponding HARQ is successfully decoded instep 2015.

When it is determined that the previous data of the corresponding HARQis not successfully decoded, the UE combines the received data withprevious data of the soft buffer of the corresponding HARQ, stores thecombined data in order to increase a decoding success rate of the data,and sets the buffer_update_ind in step 2017, and proceeds to step 2009.By contrast, when it is determined that the previous data of thecorresponding HARQ is successfully decoded, the UE determines whetherthe previous data of the corresponding HARQ is the same size as thereceived data in step 2023.

When it is determined that the sizes of the previous data of thecorresponding HARQ and the received data are not the same, the UEdetermines that the received data, which is the retransmitted data,differs from the previous data, replaces and stores the received data inthe soft buffer of the corresponding HARQ and sets the buffer_update_indin step 2025, and proceeds to step 2009.

When it is determined that the sizes of the previous data of thecorresponding HARQ and the received data are the same, the UE determinesthe duplication of the received data, discards the received data withoutstoring in the soft buffer in step 2027, and proceeds to step 2009.

The UE decodes the data in the soft buffer in step 2009 and determineswhether the decoding is successful in step 2011. When it is determinedthat the decoding is successful, the UE forwards the decoded MAC PDU andthe set buffer_update_ind to a corresponding MAC disassembly anddemultiplexing entity or to an upper layer in step 2019, and generatesand transmits ACK information for the corresponding HARQ data to the ENBin step 2021. Herein, the MAC disassembly and demultiplexing entity orthe upper layer receiving the MAC PDU may discard the MAC PDU when thebuffer_update_ind value is set to the initial value.

When it is determined that the decoding fails, the UE generates andtransmits NACK information for the corresponding HARQ data to the ENB instep 2013.

The UE ends the process.

FIG. 21 illustrates a process of a UE for determining and processingduplication of a MAC PDU using HARQ information in an LTE systemaccording to an exemplary embodiment of the present invention.

Herein, since the UE performs substantially similar operations as inFIG. 20, its operations in steps 2101-2113, 2117-2121, 2125 and 2127will not be illustrated in further detail. While decoding success orfailure of previously received data is determined in step 2015 and thenthe size of the previously received data is compared with the size ofcurrently received data when the decoding is successful in step 2023 inFIG. 20, sizes of previously received data and the currently receiveddata are compared in step 2115 and then decoding success or failure ofthe previously received data is determined in step 2123 in FIG. 21.

FIG. 22 illustrates a process of a UE for determining and processingduplication of a MAC PDU using HARQ information in an LTE systemaccording to an exemplary embodiment of the present invention.

Herein, since the UE performs substantially similar operations as inFIG. 20, its operations in steps 2201-2215, 2219, 2221, 2225 and 2227will not be illustrated in further detail. In FIG. 20, when it isdetermined that the decoding of previous data of a corresponding HARQfails in step 2015, the received data is combined and stored with thestored previous data and the buffer_update_ind is set in step 2017, andthen the data in the soft buffer is decoded in step 2009. By comparison,in FIG. 22, after received data is combined and stored with previousdata stored in a soft buffer and a buffer_update_ind is set in step2217, a UE determines whether sizes of the previous data and currentlyreceived data are the same in step 2223, rather than proceeding todecode data in the soft buffer in step 2209.

FIGS. 23, 24 and 25 illustrate a technique for preventing a malfunctionor an additional operation for a duplicated MAC PDU by immediatelydecoding data in a soft buffer when the data in the soft buffer isupdated and informing a MAC disassembly and demultiplexing entity or anupper layer of the soft buffer update only when the decoding issuccessful.

FIG. 23 illustrates a process of a UE for determining and processingduplication of a MAC PDU using HARQ information in an LTE systemaccording to an exemplary embodiment of the present invention.

Referring to FIG. 23, the UE receives downlink HARQ data from an ENB instep 2301. In step 2303, the UE confirms HARQ information, that is, NDIinformation. In step 2305, the UE determines whether the received datais retransmitted data, based on the HARQ information.

When it is determined that the received data is initially transmitteddata rather than retransmitted data, the UE replaces and stores thereceived data in a soft buffer of a corresponding HARQ in step 2307,decodes the data in the soft buffer in step 2309, and proceeds to step2311.

By contrast, when it is determined that the received data isretransmitted data, the UE determines whether previous data of thecorresponding HARQ is successfully decoded in step 2317. When it isdetermined that the previous data of the corresponding HARQ is notsuccessfully decoded, the UE combines the received data with theprevious data of the soft buffer of the corresponding HARQ and storesthe combined data in order to increase a decoding success rate of thedata in step 2319, decodes the data in the soft buffer in step 2321, andproceeds to step 2311. By contrast, when it is determined that theprevious data of the corresponding HARQ is successfully decoded, the UEdetermines whether the previous data of the corresponding HARQ is thesame size as the received data in step 2327.

When it is determined that the sizes of the previous data of thecorresponding HARQ and the received data are not the same, the UEdetermines that the received data, which is the retransmitted data,differs from the previous data, replaces and stores the received data inthe soft buffer of the corresponding HARQ in step 2329, decodes the datain the soft buffer in step 2331, and proceeds to step 2311.

When it is determined that the sizes of the previous data of thecorresponding HARQ and the received data are the same, the UE determinesthat the received data is duplicated, discards the received data in step2333, and proceeds to step 2009 without decoding.

In step 2311, the UE determines whether the data decoding of the currentsoft buffer is successful. When it is determined that the decoding issuccessful, the UE forwards the decoded MAC PDU to a corresponding MACdisassembly and demultiplexing entity or to an upper layer in step 2323and proceeds to step 2313.

When it is determined that the decoding fails, the UE determines againwhether current or past decoding is successful in step 2313. When it isdetermined that the current decoding is not successful, the UEdetermines whether previous effective decoding is successful. Herein,when it is determined that the current or past decoding succeeds, the UEgenerates and transmits ACK information for the corresponding HARQ datato the ENB in step 2325. When it is determined that the current decodingand the past decoding do not succeed, the UE generates and transmitsNACK information for the corresponding HARQ data to the ENB in step2315.

The UE ends the process.

FIG. 24 illustrates a process of a UE for determining and processingduplication of a MAC PDU using HARQ information in an LTE systemaccording to an exemplary embodiment of the present invention.

Herein, since the UE performs substantially similar operations as inFIG. 23, its operations in steps 2401-2315, 2419-2425 and 2429-2433 willnot be illustrated in further detail. Yet, after the success or thefailure of the decoding of the previously received data is determined instep 2317, the size of the previously received data is compared withthat of the currently received data when the decoding is successful instep 2327 in FIG. 23. By comparison, after sizes of previously receiveddata and currently received data are compared in step 2417, success orfailure of the decoding of the previously received data is determined instep 2427 in FIG. 24.

FIG. 25 illustrates a process of a UE for determining and processingduplication of a MAC PDU using HARQ information in an LTE systemaccording to an exemplary embodiment of the present invention.

Herein, since the UE performs substantially similar operations as inFIG. 23, its operations in steps 2501-2517, 2523, 2525 and 2529-2533will not be illustrated in further detail. In FIG. 23, when it isdetermined that the decoding of the previous data of the correspondingHARQ fails in step 2317, the received data is combined and stored withthe previous data stored in the soft buffer in step 2319, the data ofthe soft buffer is decoded in step 2321, and then the success or failureof the decoding is determined in step 2311. In FIG. 25, after receiveddata is combined and stored with previous data stored in the soft bufferin step 2519 and the data of the soft buffer is decoded in step 2521,sizes of the previous data and currently received data are compared instep 2527, rather than proceeding to determine decoding success orfailure in step 2511.

FIG. 26 is a block diagram of a UE in an LTE system according to anexemplary embodiment of the present invention.

Referring to FIG. 26, the UE includes a transceiver 2600, a receptioncontrol channel processor 2602, a HARQ soft buffer 2604, a HARQcontroller 2606, a decoder 2608, a transmission control channelprocessor 2610, a MAC disassembly and demultiplexing entity 2612, and anupper layer device 2614.

The transceiver 2600 processes transmission and reception of a PHYchannel and signals over an LTE radio channel. The reception controlchannel processor 2602 processes control channel data received in adownlink control channel, decodes and parses the received controlchannel, provides the parsed information to corresponding modules, thatis, the upper layer device 2614, the HARQ controller 2606 and thedecoder 2608, and controls the transceiver 2600.

The HARQ soft buffer 2604 replaces and stores the received data,combines and stores the previous data with currently received data, ordiscards the received data under the control of the HARQ controller2606.

The HARQ controller 2606 controls the HARQ process. The HARQ controller2606 is triggered by receiving HARQ related information from thereception control channel processor 2602. The HARQ controller 2606 alsodetermines, by using the HARQ related information, whether to replaceand store the received data to the corresponding HARQ soft buffer 2604,to combine and store the received data with the previous data, or todiscard the received data. The HARQ controller 2606 controls the HARQsoft buffer 2604 according to the determination. The HARQ controller2606 controls the decoder 2608 by determining whether to decode the dataof the HARQ soft buffer 2604. The HARQ controller 2606 forwards the HARQrelated control information to the upper layer device 2614, generatesACK/NACK information according to the decoding result of the decoder2608, and transmits the generated ACK/NACK information to thetransmission control channel processor 2610. The HARQ controller 2606determines whether the duplication occurs using the method whichdetermines whether the HARQ soft buffer 2604 is updated by replacing orcombining the received data with currently received data, or the methodwhich determines whether the decoding of the previous data is successfuland compares the sizes of the currently received data and the previousdata when the received data is retransmitted data, and determines toprocess the corresponding data. Herein, the HARQ controller 2606 maydetermine the decoding success or failure of the previous data based onthe decoding result provided from the decoder 2608.

The decoder 2608 decodes the data of the corresponding HARQ soft buffer2604 based on the decoding related information received in the receptioncontrol channel under the direction of the HARQ controller 2606, andprovides the decoding result to the HARQ controller 2606.

The transmission control channel processor 2610, which processes anuplink control channel operation, receives the information (e.g.,ACK/NACK information or Channel Quality Indication (CQI) information) totransmit in the uplink channel control from the HARQ controller 2606,processes the received information, and outputs the processedinformation to the transceiver 2600 to transmit the information to acorresponding node.

The MAC disassembly and demultiplexing entity 2612 disassembles anddemultiplexes the MAC PDU output from the decoder 2608 based on acontrol signal from the HARQ controller 2606 and duplication occurrenceinformation. More particularly, the MAC disassembly and demultiplexingentity 2612 determines whether a TA command MAC CE is duplicated byconfirming and separating the TA command MAC CE, and processes the TAcommand MAC CE according to the determination result. When duplicationoccurs, the MAC disassembly and demultiplexing entity 2612 discards theTA command MAC CE. When duplication does not occur, the MAC disassemblyand demultiplexing entity 2612 processes and controls to acquire anuplink timing synchronization by applying the TA command of the TAcommand MAC CE. Herein, based on an SN of the TA command MAC CE, the MACdisassembly and demultiplexing entity 2612 may determine whether the TAcommand MAC CE is duplicated.

The upper layer device 2614 represents a device which generates data ofthe UE to transmit and receive over a radio channel of the LTE. Theupper layer device 2614 includes applications and a control messageprocessor of the UE.

FIG. 27 is a block diagram of an ENB in an LTE system according to anexemplary embodiment of the present invention.

Referring to FIG. 27, the ENB includes a transceiver 2700, a receptionchannel and signal processor 2702, an uplink timing controller 2704, aHARQ entity 2706, a MAC assembly and multiplexing entity 2708, a MAC CEgenerator 2710, and an upper layer device 2712.

The transceiver 2700 processes transmission and reception of a PHYchannel and signals over an LTE radio channel.

The reception channel and signal processor 2702 processes channel dataand a received signal received in an uplink channel. The receptionchannel and signal processor 2702 decodes and parses the receivedchannel, provides the parsed information to the upper layer device 2712,processes an SRS and an DMRS received from the UE, and provides uplinktiming related information to the uplink timing controller 2704.

The uplink timing controller 2704 measures an uplink timing offset basedon the uplink timing information of the SRS or the DMRS provided fromthe reception channel and signal processor 2702. When determiningwhether it is necessary to correct the uplink timing offset or updatinga TA timer for a TA command update, the uplink timing controller 2704provides the timing offset value to correct to the MAC CE generator2710.

The HARQ entity 2706 controls downlink HARQ transmission of acorresponding user, and transmits a MAC PDU output from a MAC assemblyand multiplexing entity 2708 to a corresponding UE using the HARQprocess. The HARQ entity 2706 receives HARQ related information of anuplink reception control channel from the reception channel and signalprocessor 2702 and determines whether to initially transmit orretransmit corresponding HARQ data. Herein, upon determining toretransmit, the HARQ entity 2706 sets NDI information indicating thatthe corresponding HARQ data is the retransmitted data, in the HARQ datato retransmit.

The MAC CE generator 2710 generates the TA command MAC CE based on theuplink timing offset value provided from the uplink timing controller2704 and outputs the generated TA command MAC CE to the MAC assembly andmultiplexing entity 2708. More particularly, by adding the SN to the TAcommand MAC CE as illustrated in FIG. 6, the MAC CE generator 2710 mayinform the UE, receiving the TA command MAC CE, not to redundantlyprocess the TA command MAC CE.

The MAC assembly and multiplexing entity 2708 assembles and multiplexesthe MAC CEs output from the MAC CE generator 2710 and the MAC PDU dataoutput from the upper layer device 2712.

The upper layer device 2712 represents a device which generates data ofthe UE to transmit and receive over the radio channel of the LTE. Theupper layer device 2712 includes applications or a control messageprocessor of the UE.

In the LTE system, the UE determines whether the MAC PDU is duplicatedin order to prevent duplicate processing of the MAC PDU which has beennormally processed. Therefore, unnecessary operations can be avoided,the compromise of the uplink timing synchronization can be prevented,and the uplink data and signal can be reliably transmitted.

While the invention has been shown and described with reference tocertain exemplary embodiment thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims and their equivalents.

What is claimed is:
 1. A method for processing data by a terminal in amobile communication system, the method comprising: receiving data froma base station; determining whether the received data is retransmitteddata based on a new data indicator; determining whether correspondingdata has been successfully decoded when the data is retransmitted data;combining the received data with data stored in a buffer when thecorresponding data has not been successfully decoded; decoding thecombined data; determining whether decoding of the combined data is afirst successful decoding of the corresponding data when the combineddata is successfully decoded, and delivering decoded data to adisassembly and demultiplexing entity when the decoding of the combineddata is the first successful decoding of the corresponding data.
 2. Themethod of claim 1, further comprising: replacing the data stored in thebuffer with the received data when the size of the received data isdifferent from the size of the data stored in the buffer; and decodingthe data replaced in the buffer instead of the combined data, whereinthe determining of whether decoding of the combined data is the firstsuccessful decoding of the corresponding data comprises: determiningwhether decoding of the data replaced in the buffer is the firstsuccessful decoding of the corresponding data when the data replaced inthe buffer is successfully decoded.
 3. The method of claim 2, whereinthe replacing of the data stored in the buffer with the received datawhen the size of the received data is different from the size of thedata stored in the buffer comprises: comparing the size of the receiveddata with the size of the data stored in the buffer after combining thereceived data with data stored in a buffer.
 4. The method of claim 1,further comprising: storing the received data in the buffer when thereceived data is initial transmission data; decoding the received data;determining whether decoding of the received data is the firstsuccessful decoding of the corresponding data when the received data issuccessfully decoded; and delivering the decoded received data to thedisassembly and demultiplexing entity when the decoding of the receiveddata is the first successful decoding of the corresponding data.
 5. Anapparatus for processing data by a terminal in a mobile communicationsystem, the apparatus comprising: a transceiver configured to receivedata from a base station; and a controller configured to: determinewhether the received data is retransmitted data based on a new dataindicator, determine whether corresponding data has been successfullydecoded when the data is retransmitted data, combine the received datawith data stored in a buffer when the corresponding data has not beensuccessfully decoded, decode the combined data, determine whetherdecoding of the combined data is a first successful decoding of thecorresponding data when the combined data is successfully decoded, anddeliver decoded data to a disassembly and demultiplexing entity when thedecoding of the combined data is the first successful decoding of thecorresponding data.
 6. The apparatus of claim 5, wherein the controlleris further configured to: replace the data stored in the buffer with thereceived data when the size of the received data is different from thesize of the data stored in the buffer, decode the data replaced in thebuffer instead of the combined data, and determine whether decoding ofthe data replaced in the buffer is the first successful decoding of thecorresponding data when the data replaced in the buffer is successfullydecoded.
 7. The apparatus of claim 6, wherein the controller comparesthe size of the received data with the size of the data stored in thebuffer after combining the received data with data stored in a buffer.8. The apparatus of claim 5, wherein the controller is furtherconfigured to: control to store the received data in the buffer when thereceived data is initial transmission data, decode the received data,determine whether decoding of the received data is the first successfuldecoding of the corresponding data when the received data issuccessfully decoded, and deliver the decoded received data to thedisassembly and demultiplexing entity when the decoding of the receiveddata is the first successful decoding of the corresponding data.